A judge has refused to block yoga from being taught in a California school district, dismissing a claim by a small group of parents who want to end the classes because they think yoga promotes Hinduism.

Judge John Meyer said the modern practice of yoga in the US "is a distinctly American cultural phenomenon", rejecting claims made by a group of parents who believe the practice is "inherently religious".

The Encinitas Union School District, north of San Diego, implemented a pilot version of the yoga program at nine schools in 2011, before incorporating it into the district-wide curriculum in January this year.

"A reasonable student would not objectively perceive that Encinitas School District yoga does advance or promote religion," said Meyer, in a ruling on Monday. The curriculum uses "kid-friendly" terms including "gorilla", "turtle" and "peacock" to describe poses instead of the traditional names.

Of the school district's 5,000 students, between 40 and 45 were taken out of the classes by their parents. The case petitioners are backed by the National Center for Law & Policy (NCLP), a Christian civil liberties group that released a four-page document (pdf) listing reasons why it thought the district was promoting a religious form of the activity.

"Religious freedom is one of the brightest stars in the constellation of liberties we enjoy as American citizens," said Dean Broyles, NCLP president and lead attorney for the petitioners, in a statement. He said yoga endorses Hindu beliefs and discriminates against other religions, therefore violating the separation of church and state.

The NCLP's complaints were concentrated on the Jois Foundation, an Encinitas non-profit that gave the district a $533,000 grant for a program which is also receiving support from the University of Virginia and University of San Diego, which are researching the effects of yoga on children's health. The foundation was created in memory of Krishna Pattabhi Jois, who popularized the Ashtanga school of yoga.

"No matter who has won or lost today at this level, one this is clear: this is not the end of the road for this case or the last word regarding the fate of yoga in public education – this is only the beginning," said Broyles.

The NCLP's yoga expert, Candy Gunther Brown, who is a professor of religious studies, testified that yoga indoctrinates Hindu religious practices whether the individual knows it or not. She also cited research that suggests yoga changes people's thoughts, but the judge said: "Dr Brown has an obvious bias and can almost be called being on a mission against yoga."

As part of the country's wider dialogue on the separation of church and state, a high school in Michigan banned postgame prayer last week, after the American Civil Liberties Union filed a complaint against the practice. The school's football team participated in student-led prayer for nearly 11 years, according to The Oakland Press.

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